user-guide/00-introduction: Describe *-installer types

Add short hint on the difference between
`image-installer` and `live-installer`.

docs/user-guide/00-introduction.md

@@ -44,8 +44,8 @@ Image Builder can create images in multiple output formats shown in the followin
 | IoT Simplified Installer | iot-simplified-installer | .iso      | 
 | IoT AMI | iot-ami | .ami      | 
 | IoT VMDK | iot-vmdk | .vmdk      | 
-| Installer | image-installer | iso     | 
-| Installer | live-installer | iso     | 
+| Bare installer including target image separately | image-installer | .iso     | 
+| Full live system of the target running the installer | live-installer | .iso     | 
 | Oracle Cloud Infrastructure | oci     | .qcow2      | 
 
 To check the supported types, run the command: